Facial attractiveness played a major role in shaping human evolution, scientists at the Natural History Museum have discovered.
Studies on our fossil ancestors have shown our choice of sexual partner has shaped the human face.
Men have evolved short faces between the brow and upper lip. This exaggerates the size of their jaw, the flare of their cheeks and their eyebrows.
'The evolution of facial appearance is central to understanding what makes men and women attractive to each other,' says Dr Eleanor Weston, fossil expert at the Museum.
'We have found the distance between the lip and brow was probably immensely important to what made us attractive in the past, as it does now.'
The canine teeth have also shrunk, so men look less threatening to competitors, yet attractive to mates.
At puberty, the region between the mouth and eyebrows, known as upper facial height, develops differently in men and women.
Unlike other facial features, however, this difference cannot be explained simply in terms of men being bigger than women.
In spite of their larger size men have an upper face similar in height to a female face, but much broader. These differences can be found throughout human history.
As a result, a simple ratio of measures could be used to calculate facial attractiveness in a biological and mathematical way.
The paper is available online in PLoS ONE , an open-access journal.